Large morphological interpopulation variability and differences in chromosome numbers suggest that several species may be confused under the name M. anguillicaudatus. Some populations from Viet Nam earlier identified as this species are in fact M. multimaculatus and M. tonkinensis.

Justification:
A widespread species that has been very widely introduced. Although there is some evidence that the species has declined in parts of the species' native range, the species is considered Least Concern at present.

The species is known from eastern Asia, from eastern Russia (Siberia (Tugur and Amur drainages) and Sakhalin), Korea, Japan, and eastern China south to northern Viet Nam (to the Ma River; Masuda et al. 1984, Zheng 1989) and Lao PDR (native in the Nam Ma basin, also present in the Nam Theun of the Mekong basin but is probably introduced there; Kottelat 2001, M. Kottelat pers. comm. 2011).It has been very widely introduced through the ornamental fish trade, and as a food and a live angling bait fish; Germany (Rhine), Italy (Ticino, north of Milan), Spain, the Aral Sea basin, North America (widely introduced on the eastern and western coasts of USA), Kazakhstan, Uzbekistan, Turkmenistan, the Philippines, Australia and Hawaii (as a foodfish by immigrants).

Found in still or gently flowing rivers, lakes and ponds with muddy bottoms. The species is widely associated with agricultural landscapes especially rice fields and field ditches (Kano et al. 2010, Qin et al. 2010). Feeds on small aquatic organisms and can breathe air to supplement oxygen in oxygen-depleted waters.

Commonly used by anglers as live bait and also found in the aquarium trade. The species can be found in large quantities in markets, and it is also cultivated (M. Kottelat pers. comm. 2011). Utilised in traditional Chinese medicine for treatment of a range illnesses including hepatitis, carbuncles, inflammations and cancers (Qin et al. 2010), and production is high (hence the need for cultivation) in China and Korea.

Kano et al. (2010) record that the species has been impacted by agricultural intensification, especially the use of agrochemicals, and the species has declined in parts of China as a result of ecosystem degradation (Qin et al. 2010). The species global population is expanding through introductions, and is not through to be threatened.

Qin, C.G., Huang, K.X., and Xu, H.B. 2010. Protective effect of polysaccharides from the loach on the in vitro and in vivo peroxidative damage of hepatocyte. Journal of Nutrirional Biochemistry 15: 592-597.